Fracture Mechanism in Overlying Strata during Longwall Mining

Table 1

Physicomechanical parameters of coal and rocks in numerical simulation.

Lithology	Density (kg/m^3)	Elastic modulus (GPa)	Poisson’s ratio μ	Cohesion c^b (MPa)	Internal friction angle φ^b (°)	Tensile strength σt^b (MPa)
Sandstone1	2700	20	0.30	4.0	39	3.40
Sandstone2	2750	25	0.28	8.0	40	7.80
Mudstone	2400	4	0.33	1.0	33	1.08
Coal	1800	2.5	0.35	0.8	25	1.02